. >> reporter: in a letter to obama administration officials, two top republican members of congress questioned why tamerlan remained at liberty in this country to commit the boston attack. and whether the bureau could have done more to watch them. >> we can't be politically correct. we have to say, has radicalization extended into the chechen community? >> reporter: the fbi says there was little they could do to legally monitor tamerlan tsarnaev once they -- initially determined he was not a threat. but one question congressional investigators have is, having gotten that initial tip from russian intelligence, why didn't anybody at the bureau notice those radical youtube postings on the internet? lester? >> we're going to get into that right now, michael isikoff. don barrelli is a former senior fbi official, now the chief operating officer of a security consulting firm. don, good morning. great to see you. >> good morning, lester. >> should have, could have. those questions always asked following an attack like this. >> yep. >> this older brother was on the fbi's radar. should he hav